120 lines
4.6 KiB
Scheme
Executable file
120 lines
4.6 KiB
Scheme
Executable file
#! /bin/sh
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# -*-scheme-*-
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exec ${GUILE-guile} -L $(dirname 0) -e '(diff)' -s "$0" "$@"
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!#
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;;; Mes --- Maxwell Equations of Software
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;;; Copyright © 2016,2017,2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
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;;;
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;;; mes-snarf.scm: This file is part of Mes.
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;;;
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;;; Mes is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; Mes is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with Mes. If not, see <http://www.gnu.org/licenses/>.
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(define-module (diff)
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#:use-module (srfi srfi-1)
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#:use-module (srfi srfi-9)
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#:use-module (ice-9 rdelim)
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#:export (main))
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(cond-expand
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(mes
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(define %scheme "mes"))
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(guile-2
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(define %scheme "guile")
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(define-macro (mes-use-module . rest) #t))
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(guile
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(use-modules (ice-9 syncase))
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(define %scheme "guile")
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(define-macro (mes-use-module . rest) #t)))
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(mes-use-module (mes guile))
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(format (current-error-port) "diff[~a]...\n" %scheme)
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(define (plus a)
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(string-append "+" a))
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(define (minus a)
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(string-append "-" a))
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(define (keep a)
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(string-append " " a))
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(define-record-type <hunk> (make-hunk context after removed added)
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hunk?
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(context hunk.context)
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(after hunk.after)
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(removed hunk.removed)
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(added hunk.added))
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(define (hunk->lines o)
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(append `(,(format #f "@@ -~a,~a +~a,~a" (length (hunk.removed o)) (+ 3 (car (hunk.context o))) (length (hunk.added o)) (+ 3 (cadr (hunk.context o))))
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,@(map keep (filter identity (cddr (hunk.context o)))))
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(map minus (hunk.removed o))
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(map plus (hunk.added o))
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(map keep (hunk.after o))))
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(define (safe-list-head lst n)
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(list-head lst (min n (length lst))))
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(define (line-equal? a b)
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(equal? (string-trim-right a) (string-trim-right b)))
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;; naive diff
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(define (diff a b)
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(let ((a-lines (string-split (with-input-from-file a read-string) #\newline))
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(b-lines (string-split (with-input-from-file b read-string) #\newline)))
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(let loop ((context '(1 1 #f #f #f)) (a-lines a-lines) (b-lines b-lines))
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;;(format (current-error-port) "loop context=~s\n" context)
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(cond ((and (null? a-lines) (null? b-lines)) '())
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((null? a-lines)
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(list (make-hunk context (safe-list-head a-lines 3) '() b-lines)))
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((null? b-lines)
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(list (make-hunk context (safe-list-head a-lines 3) a-lines '())))
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((line-equal? (car a-lines) (car b-lines))
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(loop `(,(1+ (car context))
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,(1+ (cadr context))
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,@(cdddr context)
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,(car a-lines))
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(cdr a-lines) (cdr b-lines)))
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(else
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(cond ((and (pair? (cdr b-lines)) (line-equal? (car a-lines) (cadr b-lines)))
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(cons (make-hunk context (safe-list-head a-lines 3) '() (list (car b-lines)))
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(loop `(,(+ 1 (car context))
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,(+ 2 (cadr context))
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,@(cdddr context)
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,(car a-lines))
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(cdr a-lines) (cddr b-lines))))
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((and (pair? (cdr a-lines)) (line-equal? (cadr a-lines) (car b-lines)))
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(cons (make-hunk context (safe-list-head a-lines 3) (list (car a-lines)) '())
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(loop `(,(+ 2 (car context))
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,(+ 1 (cadr context))
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,@(cddddr context)
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,(car a-lines)
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,(cadr a-lines))
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(cddr a-lines) (cdr b-lines))))
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(else (cons (make-hunk context (safe-list-head a-lines 3) (list (car a-lines)) (list (car b-lines)))
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(loop `(,(1+ (car context))
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,(1+ (cadr context))
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,@(cdddr context)
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,(car a-lines))
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(cdr a-lines) (cdr b-lines))))))))))
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(define (main args)
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(let* ((files (cdr args))
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(files (if (string-prefix? "-" (car files)) (cdr files) files))
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(hunks (apply diff (list-head files 2))))
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(when (pair? hunks)
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(display (string-join (append-map hunk->lines hunks) "\n"))
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(newline)
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(exit 1))))
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